Over the past few days, the cryptocurrency market has been absolutely hammered. A week ago, the value of all cryptocurrencies was well in excess of $700 billion -- now it's $430 billion. None of the major currencies have been spared. Bitcoin (BTC-USD), Ethereum (ETH-USD), and Ripple (XRP-USD), and some of the best-performing alternative cryptocurrencies of 2017 and early 2018 are getting crushed even worse.

Today's cryptocurrency prices

Here's a look at the five largest cryptocurrencies by market capitalization, and how much each has changed over the past 24 hours, as well as over the past week.

Cryptocurrency Name (Code)

Price in U.S. Dollars

Day's Change

Weekly Change

Bitcoin (BTC)

$9,536.00

(18.3%)

(33.3%)

Ethereum (ETH)

$799.50

(26.5%)

(39.6%)

Ripple (XRP)

$0.92

(31.4%)

(52.4%)

Bitcoin Cash (BCH)

$1,401.80

(27.4%)

(45.5%)

Cardano (ADA)

$0.46

(27.5%)

(39.6%)

Data source: www.investing.com. Prices and daily changes as of 10:15 a.m. on January 17, 2018, and prices are rounded to the nearest cent where appropriate.

Bitcoin drops below $10,000, Ethereum below $1,000

The two largest cryptocurrencies, bitcoin (BTC-USD) and Ethereum (ETH-USD), both fell below key psychological levels. Bitcoin fell below $10,000 for the first time since November 30, and it now trades for less than half of its all-time high of $19,343 reached in December. And Ethereum dropped sharply through the key $1,000 level after reaching its record high just days ago.

Businessman watching red arrow crash through the floor.

Image Source: Getty Images.

Major altcoins are getting crushed

The carnage isn't limited to bitcoin (BTC-USD) and Ethereum (ETH-USD). In fact, many of the major alternative cryptocurrencies, or altcoins, are faring much worse. Ripple (XRP-USD), which has been one of the market's top performers in recent months on news of partnerships with American Express, Santander, and MoneyGram International, is off by more than 30% over the last 24 hours alone. Ripple (XRP-USD) also broke through a key level, with its coins falling below $1.00 each.

Beyond the top five, the declines are just as bad, if not worse. Stellar and NEM are both down about 35% today, and Tron is worth less than one-fourth of its January 5 peak.

Just a sell-off, or the beginning of a crypto-crash?

The recent drop was initially triggered by fears that South Korea and China could clamp down on cryptocurrency trading, and it appears that this is still the reason for the downward movement.

Before anyone panics, it's important to realize that this isn't exactly unusual activity in the cryptocurrency markets. Bitcoin and the others have experienced price drops of this magnitude before, and the recent moves in many cryptocurrencies have been even more dramatic, just in the opposite direction. In short, volatility like this is the rule, not the exception.

Having said that, it remains to be seen if this is simply a bump in the road for cryptocurrencies, or a more longer-lasting price correction.

Matthew Frankel owns shares of American Express. The Motley Fool recommends American Express. The Motley Fool has a disclosure policy.